K & B mock exam question typo

[Francis Palattao]

public class Test{
public static void main (String []args)
long [][]a1;
long []a2[];
a2 = new long[3][];
a1 = a2; // Line 6
System.out.println(a1[0][0]);
}
}

This should be runtime error but in the mock exam it says the answer is Compilation error at line 6.

Is it a typo?

[Jeff Bosch]

It's actually a runtime exception (not error) because the program tries to access an uninitialized array element. (You're also missing an opening brace at main().)